1. Field of the Invention
This invention relates to a throttle valve controller having means capable of coping with cases where failures have occurred in a plurality of accelerator sensors.
2. Description of the Related Art
A throttle valve control device or controller for electronically controlling the degree of opening of a throttle valve by a throttle actuator has been widely used in a recent vehicle. Since the throttle valve controller controls the degree of opening of the throttle valve while following the amount of depression of an accelerator pedal, the amount of depression of the accelerator pedal is measured by a corresponding accelerator sensor. Particularly when the accelerator sensor produces trouble for some reason, the vehicle might produce a dangerous driven state. Therefore, a plurality of accelerator sensors have heretofore been individually attached to the accelerator pedal.
Thus, when a failure or trouble has occurred in any of the plurality of accelerator sensors where the plurality of accelerator sensors are individually attached thereto, the subsequent treatment of this failure is very important from a safety standpoint. According to Japanese Patent Application Laid-Open No. 4-214949, for example, when trouble exists in two potentiometers equivalent to the aforementioned accelerator sensors, an electronic control device is deactivated or allowed to continue its function based on a signal outputted from the sensor thereof that is accurately functioning, thereby avoiding the occurrence of the dangerous driven state.
However, when an input value outputted from the other potentiometer falls within an improper range even when an input value outputted from one potentiometer falls within a normal or proper range, they lead no longer to a so-called double potentiometer configuration. There may be cases where the trouble of each potentiometer, which can be detected by making a comparison between the input values outputted from the two potentiometers, cannot be detected. Thus, even if the input value outputted from one potentiometer falls within the normal range, there may be cases in which the potentiometer cannot be determined or judged as being accurately functioning. That is, as has been described in Japanese Patent Application Laid-Open No. 4-214949, the dangerous driven state might not be avoided from occurring even if the electronic control device is caused to continue its function based on the signal outputted from the sensor that is accurately functioning.